Prestressed concrete roadway

Abstract

A concrete slab is provided with prestressing cables to be post-tensioned upon setting of the concrete. The post-tensioning cables or strands are equally spaced on predetermined centers and are angled with respect to the longitudinal axis of the slab. All of the strands are parallel and are substantially co-planar with all other strands. The angle between the longitudinal axis of the slab and the strands ranges from approximately 2° to approximately 60°. This application is a continuation-in-part application of an application entitled "PRESTRESSED CONCRETE ROADWAY", filed July 12, 1977, assigned Ser. No. 814,993, and describing an invention made by the present inventor now abandoned.

I claim: 
     
       1. A section of prestressed concrete roadway comprising: a. a poured-in-place concrete slab section having predetermined thickness, width, and length and having a longitudinal axis, said poured-in-place concrete slab section having first and second opposed edges;   b. a plurality of post-tensioned diagonal strands distributed at predetermined intervals in said concrete slab section, each of said post-tensioned diagonal strands being substantially parallel to all of the others of said post-tensioned diagonal strands, each of said post-tensioned diagonal strands being oriented at a predetermined angle with respect to said longitudinal axis, each of said post-tensioned diagonal strands having first and second ends, respectively, said first end of each of said post-tensioned diagonal strands being anchored into said poured-in-place concrete slab section along said first edge, said second end of each of said post-tensioned diagonal strands being anchored into said poured-in-place concrete slab section along said second edge, said poured-in-place concrete slab section containing no post-tensioned diagonal strands which are not parallel to each of said plurality of post-tensioned diagonal strands;   c. first anchoring means attached to each of said first ends for anchoring said first ends into said first edge of said poured-in-place concrete slab section; and   d. second anchoring means attached to each of said second ends for anchoring said second ends into said second edge of said poured-in-place concrete slab section, said first and second anchoring means maintaining predetermined effective tensile forces in each of said diagonal strands, said predetermined effective tensile forces acting to produce a longitudinal compressive force in said poured-in-place concrete slab section, said predetermined effective tensile forces also acting to produce a shear force in said poured-in-place concrete slab section, said predetermined angle being selected such that said longitudinal compressive force exceeds a predetermined magnitude and said shear stress is sufficiently low to avoid significiant weakening of said poured-in-place slab section; whereby, all of said first ends of said post-tensioned diagonal strands are oriented in the same direction along said first edge surface to permit rapid post-tensioning of said post-tensioned diagonal strands without interference from others of said post-tensioned diagonal strands and without requiring reorienting of equipment utilized to perform said post-tensioning of said diagonal strands.     
     
     
       2. The section of prestressed concrete roadway of claim 1 wherein all of said strands are positioned substantially co-planar with respect to each other. 
     
     
       3. The section of prestressed concrete roadway of claim 2 wherein all of said strands form an angle in the range from approximately 2° to approximately 60° with respect to said longitudinal axis. 
     
     
       4. The section of prestressed concrete roadway of claim 2 wherein said section is a section of prestressed concrete railroad roadway and wherein said strands each form an angle of approximately 45° with respect to said longitudinal axis. 
     
     
       5. The section of prestressed concrete roadway of claim 2 wherein all of said strands are positioned in said slab at a depth equal to approximately one half of said thickness. 
     
     
       6. The section of prestressed concrete roadway of claim 1 wherein said predetermined effective tensile forces are approximately twenty-five thousand pounds. 
     
     
       7. The section of prestressed concrete roadway of claim 6 wherein said plurality of post-tensioned cables are distributed on approximately twenty-four inch centers along said longitudinal axis. 
     
     
       8. A method of making a section of prestressed concrete roadway containing a plurality of post-tensioned diagonal strands, said method comprising the steps of: a. pouring a first quantity of concrete into a region bounded by pre-positioned forms disposed along the edges of said section of prestressed concrete roadway;   b. positioning a plurality of diagonal strands contained in said section of prestressed concrete roadway substantially parallel to each other in said region, each of said diagonal strands being substantially enclosed in flexible plastic sheathing, no diagonal strands which are not substantially parallel to said plurality of diagonal strands being positioned in said section of prestressed concrete roadway;   c. pouring a second quantity of concrete into said region to cover said positioned post-tensioned diagonal strands;   d. curing all of said concrete for a predetermined time; and   e. successively tightening anchors of each of said post-tensioned diagonal strands to produce at least a predetermined tensile force in each of said post-tensioned diagonal strands by means of a tensioning machine without reorienting the direction of an anchor-engaging tensioning element of said tensioning machine; whereby, all of said first ends of said post-tensioned diagonal strands are oriented in the same direction to permit rapid post-tensioning of said post-tensioned strands without interference from others of said post-tensioned diagonal strands and without requiring reorienting of equipment utilized to perform said post-tensioning of said diagonal strands.